In the field of display technology, a display substrate mainly includes a color-film substrate and an array substrate which are arranged by aligning and assembling. There is mainly a color filter (i.e., a patternized color resin layer for manufacturing a color filter) provided on the color-film substrate, and there is mainly a pixel array provided on the array substrate. In recent years, as people's demand for a display panel of high aperture ratio and high brightness increases, a technology in which a color filter is directly formed on an array substrate (Color filter On Array, which is simply referred to as COA). A color filter array substrate formed by the COA technology is referred to as a COA substrate.
Both manufacture of a color-film substrate and manufacture of a COA substrate include a procedure of manufacturing a color filter, a procedure of manufacturing a black matrix, and a procedure of manufacturing a via in a color resin layer for manufacturing a color filter. The color filter, the black matrix, and the color resin layer for manufacturing a color filter are all photoresist layers.
In the prior art, when a color filter, a black matrix, or a via is formed on a photoresist layer, a resin layer is exposed to light by using a mask corresponding to a pattern, and then the exposed resin layer is developed to obtain the pattern. During exposure, the mask is located on an exposure apparatus, and the exposure apparatus is moved to make the mask be close to a photoresist layer to be exposed (i.e., exposure is performed by using a large area proximity exposure mode), to obtain a black matrix having a certain line width, a slit between adjacent color filters, or an aperture having a certain width.
In the prior art, a mask generally has a single-layer structure, and the mask is provided with a light transmissive region and a light non-transmissive region. Since the minimum distance between an apparatus and a film layer to be exposed is about 300 μm, exposure light will experience a diffraction phenomenon during passing through a slit or a via to irradiate a photoresist layer under the mask, so that an exposed region on the photoresist layer is larger than the light transmissive region of the mask. Thus, the size of the resultant aperture, slit, or black matrix is larger.
As the number of pixels of a display increases, a demand for graphic fineness increases. In the prior art, the fineness of a pattern obtained by forming a color filter, a black matrix, or a via on a photoresist layer has failed to meet requirements, because application the pattern obtained in such a way to a display product will limit the aperture ratio of a pixel.